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Qualifying a new SMT automated assembly line

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#56899

Qualifying a new SMT automated assembly line | 13 October, 2008

Hi,

I would like to ask if there's a guideline/specification on what is needed to qualify a new SMT automated assembly line?

Is there any standards i can refer to? IPC or JEDEC? Is there a reference number for the standards so i can refer to as well?

Thanks a lot and looking forward to replies.

Kev

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#56911

Qualifying a new SMT automated assembly line | 14 October, 2008

Hi, I have been at both ends of this business. I installed lines and have been in manufacturing for some 25 years.

Do not go by the test boards that the installer or OEM uses. these boards are too broad and loose for any kind of guide line to establish good placement and or soldering. have one of your products ready to run. have your parts pulled and be ready as they will tell you they are pressed for time. Using your own product use IPC guidlines to figure out if the equipment is working to standard. another trick they may use is when placing smt parts and they are not placing dead center thats a big problem. Leadfree is not as forgiving as lead. lead could pull a part in at reflow. Not so with leadfree. they must be as close to center as possable as with the leadfree it is not going to pull in like lead would. Dont accept or sign off on your equipment if it cant place exactly. you will regreat it later.

good luck

Tim Bickford

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#56969

Qualifying a new SMT automated assembly line | 16 October, 2008

Hi,

I think the standard was IPC 6850. But I will recommend to go directly with the sigma test. Place parts with the machine and measure the placement accuracy on another machine. 4-5sigma at 50um should be a good machine. If they have sigma in their specs, they should prove it in front of you.

Regards, Emil

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#56985

Qualifying a new SMT automated assembly line | 18 October, 2008

Use a Cpk study on your screen printer. Deviation from print to print.

Most reutable surface mount machine companies will supply you with their Cpp study they performed on your machine before they shipped it.

On ovens use your profiler. You can determine Cpk on peak temps, or times above liquidous - what ever.

You'll find that this kind of paper work is only good for auditors or pencil pushers that have no clue how solder works yet are in charge to make such calls.

Never use a Cpk study to determine your machines capabilities - as Cpk only determines repaetability. If you have new equipment perform your Cpk and then jump in and see how far you stretch your process windows. This information is far more valuable than any Cpk study. I always see a Cpk study as driving a car in a perfect world. I push the pedal all the way down and it goes 55 MPH - I push the break and it stops exactly in 120 feet of distance. In the real world I can't always drive a constant 55MPH and sometime I have to stop under a distance of 120 feet. It's good to know it will always do 55 MPH and stop at 120 feet, but in the real world you will never use it. (Oops, I just fell off my soap box - or was I pushed off?)

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